Several techniques have been used in the past for the treatment of tissue including diseased tissue, such as cancer, to remove, destroy, or otherwise minimize the growth of the diseased tissue. For example, traditional methods of treating diseased prostate tissue include high intensity focused ultrasound (“HIFU”), radiation, surgery, Brachytherapy, cryoablation, hormonal therapy, and chemotherapy. Described herein are improved apparatus and method for treating tissue with high intensity focused ultrasound.
The treatment of tissue with HIFU is known. There are, for example, the techniques and apparatus described in U.S. Pat. Nos. 4,084,582; 4,207,901; 4,223,560; 4,227,417; 4,248,090; 4,257,271; 4,317,370; 4,325,381; 4,586,512; 4,620,546; 4,658,828; 4,664,121; 4,858,613; 4,951,653; 4,955,365; 5,036,855; 5,054,470; 5,080,102; 5,117,832; 5,149,319; 5,215,680; 5,219,401; 5,247,935; 5,295,484; 5,316,000; 5,391,197; 5,409,006; 5,443,069; 5,470,350; 5,492,126; 5,573,497; 5,601,526; 5,620,479; 5,630,837; 5,643,179; 5,676,692; 5,762,066; and 5,840,031. The disclosures of these references are hereby incorporated herein by reference.
Although the techniques, methods, and apparatus discussed herein have applicability to the treatment of tissue in general, this discussion will focus primarily on the treatment of prostate tissue including Benign Prostatic Hyperplasia (BPH) and prostatic cancer. However, the disclosed apparatus and methods may find applications in localization and treatment of a wide range of diseases which manifest themselves in a localized or “focal” manner, including cancers of the breast, brain, liver, and kidney. As explained herein, the disclosed apparatus uses a transrectal probe, but may be used with other types of probes including a transesophageal, laparoscopic or transvaginal probe.
As used herein the term “HIFU Therapy” is defined as the provision of high intensity focused ultrasound to a portion of tissue at or proximate to a focus of a transducer. It should be understood that the transducer may have multiple foci and that HIFU Therapy is not limited to a single focus transducer, a single transducer type, or a single ultrasound frequency. As used herein the term “HIFU Treatment” is defined as the collection of one or more HIFU Therapies. A HIFU Treatment may be all of the HIFU Therapies administered or to be administered, or it may be a subset of the HIFU Therapies administered or to be administered. As used herein the term “HIFU System” is defined as a system that is at least capable of providing a HIFU Therapy.
A probe housing a transducer is used to position a transducer proximate to the prostate of the patient. HIFU therapy requires a coupling medium (typically water) to couple the HIFU energy generated by the transducer into the body. At high intensities, ultrasound energy can create cavitation bubbles in the coupling medium, which interfere with the propagation of the sound waves, reducing their intensity and defocusing the beam. Furthermore, the cavitation bubbles can coalesce into larger air bubbles and accumulate on surfaces (such as an acoustic membrane) located between the transducer and the target tissue, effectively blocking the propagation of ultrasound into the body, or creating an interface mismatch at which undesired energy will accumulate at undesired locations, such as at the rectal wall. To reduce the likelihood of these effects degassed water is used as the coupling medium. As stated in U.S. Pat. No. 5,762,066, an acceptable level of degassed water for HIFU Therapy is water having a dissolved oxygen level of less than 3 parts per million (ppm).
Traditionally, degassed water is used in HIFU Therapy that is degassed prior to the treatment by known methods, such as boiling and vacuum degassing using a Nold DeAerator (Geokon, Inc., Lebanon, N.H. 03766). This requires the procurement of degassed water in advance. The fluid pathway of the HIFU System is traditionally filled/primed with this degassed water prior to commencing a HIFU Treatment. Over time, however, this degassed water will slowly ingas, as air permeates back into the degassed water through the connecting tubes, the acoustic membrane, and other pathways. Furthermore, during the filling/priming of the fluid pathway, air bubbles may be introduced into the degassed water contributing to ingasing the water. Both result in an increase in the level of dissolved gases in the degassed water which increases the chances of creating cavitation in the water during HIFU Therapy, especially as the HIFU Treatment progresses.
In addition, small bubbles introduced into the fluid pathway of a HIFU System have traditionally been difficult to remove as the bubbles tend to adhere to inside surfaces that are not easily accessible during probe preparation steps, such as the inside of the probe tip and the inside of the chilling system. Typically, during probe preparation, these bubbles are coaxed/manipulated in such a way by probe shaking and probe tip tapping so that a pump which circulates the water eventually removes the bubbles from their current location (i.e. the probe tip) and the bubbles end up at the top of a water reservoir, at which point they are unable to flow back into the probe tip to interfere with the treatment, as the water reservoir acts as a bubble trap. However, if all the bubbles are not removed, some bubbles may end up again in the probe tip in front of the HIFU beam negatively interfering with the delivery of HIFU Therapy to the patient.
In an exemplary embodiment of the present invention, a HIFU System is provided having a fluid circulation system including a degasser.
In another exemplary embodiment of the present invention, an apparatus for treating tissue is provided. The apparatus comprising a probe and a fluid circulation system. The probe including a transducer which is positionable proximate to the tissue, the transducer being configured to emit ultrasound energy and to sense ultrasound energy, a positioning member coupled to the transducer and configured to position the transducer relative to the tissue, and a fluid inlet and a fluid outlet. Both the fluid inlet and the fluid outlet being in fluid communication with a fluid pathway including an area adjacent a face of the transducer. The fluid circulation system being in fluid communication with the fluid inlet and the fluid outlet of the probe. The fluid circulation system including a pump configured to circulate a fluid throughout the fluid circulation system and the fluid pathway of the probe; a chiller configured to reduce a temperature of the fluid; a degasser which is configured to remove dissolved gases from the fluid; and a fluid adjustment member including a fluid reservoir. The fluid adjustment member being configured to both add additional fluid to the fluid circulation system and remove fluid from the fluid circulation system.
In a further exemplary embodiment of the present invention a method of preparing a HIFU system having a transrectal probe to provide treatment to the prostrate area of a patient is provided. The transrectal probe including a fluid pathway which includes an area a face of a therapy transducer. The method comprising the steps of: providing a fluid circulation system in fluid communication with the fluid pathway of the transrectal probe, the fluid circulation system including a pump configured to circulate a fluid through the fluid circulation system and the fluid pathway of the transrectal probe and a degasser which is configured to remove dissolved gases from the fluid passing through the degasser, the degasser including a vacuum pump; and electrically coupling the vacuum pump and the pump together such that each receives electrical power at generally the same time.
In yet another exemplary embodiment of the present invention, an apparatus for treating the prostrate from a position in a rectum of a patient is provided. The apparatus comprising a transrectal probe including an expandable acoustic membrane covering at least a portion of the probe and a transducer positioned behind the expandable acoustic membrane. The transducer being configured to emit ultrasound energy and to sense ultrasound energy. The apparatus further comprising a controller operably coupled to the transducer. The controller being configured to operate the transducer in an imaging mode wherein at least one image of the tissue is obtained from ultrasound energy sensed by the transducer and in a therapy mode wherein a plurality of treatment sites are treated with a HIFU Therapy with the transducer. The apparatus further comprising a fluid circulation system in fluid communication with a fluid pathway including an area adjacent a face of the transducer between the transducer and the acoustic membrane. The fluid circulation system including a pump configured to circulate a fluid throughout the fluid circulation system and the fluid pathway of the probe; a chiller configured to reduce a temperature of the fluid; a degasser configured to remove dissolved gases from the fluid, the degasser including a vacuum pump; and a fluid adjustment member including a fluid reservoir. The fluid adjustment member being configured to both remove fluid from the fluid circulation system and to add additional fluid to the fluid circulation system, wherein a first portion of the additional fluid is to be introduced to the fluid to expand the expandable acoustic membrane to contact the rectum of the patient when the probe is positioned in the rectum of the patient and a second portion of the additional fluid is to be introduced into the fluid to further expand the expandable acoustic membrane to position the transducer relative to the prostrate of the patient in a direction generally transverse to a longitudinal axis of the transrectal probe.
Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiments exemplifying the best mode of carrying out the invention as presently perceived.